1. Field of the Invention
The present invention relates generally to electrophotographic imaging devices and, more particularly, to fusers of electrophotographic imaging devices.
2. Description of the Related Art
In the electrophotographic (EP) imaging process used in printers, copiers and the like, a photosensitive member, such as a photoconductive drum or belt, is uniformly charged over an outer surface. An electrostatic latent image is formed by selectively exposing the uniformly charged surface of the photosensitive member. Toner particles are applied to the electrostatic latent image, and thereafter the toner image is transferred to the media intended to receive the final permanent image. The toner image is fixed to the media by the application of heat and pressure in a fuser. A fuser may include a heated roll and a backup roll forming a fuser nip through which the media passes. A fuser may also include a fuser belt and an opposing backup member, such as a backup roll.
As the regulation of office/home printers becomes focused more on the conservation of energy and the environmental impacts of energy usage, the need for so called “instant-on” fusers becomes critical. Instant on fusers do not require idle modes where the fuser is maintained at an elevated temperature through periodic applications of power. For typical color machines the power usage in idle or standby mode is 150-200 watts. The fuser is the main source of power usage in a printing device, typically around 120-170 watts in an idle mode. Currently the Energy Star/Blue Angel certifications allow for such a mode, but in the future there is discussion of eliminating the idle mode feature and requiring energy usage of less than 45 watts when not printing. This will prevent any current fixing roller fuser from being able to either pass Energy Star/Blue Angel certification or have a quick warm up time. Current color fixing roller fusers have a cold start warm up time in the range of 2 to 4 minutes.
Prevailing instant on fuser technology uses either a ceramic heater or an inductive heating system. For maintaining print quality in color printing, instant on fusers require an expensive, elastomer coated belt. In color applications, elastomer coatings are required to generate compliance in the fusing nip to produce high print quality on images with multiple layers of toner. To minimize thermal constraints, these elastomer coated belts are typically made of a metallic base layer (required for inductive heating), rather than the standard polyimide belts used in mono ceramic heater applications. Metallic, elastomer coated, and often PFA sleeved belt costs may be up to five times more than a standard polyimide based belt with only a PFA/PTFE coating (PFA is a perfluoroalkyl vinyl ether copolymer, and PTFE is polytetrafluoroethylene), What is needed in the art is a fuser which allows for the use of a polyimide base layer belt for color printing, provides improved gloss and transparency quality for high speed printing with a ceramic heater, and provides improved print media release properties with less print artifacts.